The present invention relates to personal mobile computing devices commonly known as handheld portable computers. More particularly, the present invention relates to a system and a method for searching for changes and deletions of objects between a mobile device and a desktop computer.
Mobile devices are small electronic computing devices often referred to as personal desktop assistants. One such mobile device is the Handheld PC (or xe2x80x9cH/PCxe2x80x9d) based on and including the Windows CE(copyright) brand operating system sold by Microsoft Corporation of Redmond, Wash. Although small, a wide variety of computing tasks and applications can be performed by such mobile devices, such as word processing, spread sheet programs, personal money managers, personal information managers (PIMs) and games, to name a few. In many respects, these programs are very similar to programs that reside on an individual""s desktop computer. In some applications, the mobile device may not have as many functions as available on a desktop computer but, nevertheless, are quite valuable as a means for updating and changing data in the field where even a laptop computer may not be available or used conveniently.
PIMs typically include applications which enable the user of the mobile device to better manage scheduling and communications, and other such tasks. Some commonly available PIMs include scheduling and calendar programs, task lists, address books, and electronic mail (e-mail) programs. Some commonly commercially available PIMs are sold under the brand names Microsoft Schedule+(copyright) and Microsoft Outlook(copyright) and are commercially available from Microsoft Corporation of Redmond, Wash.
It is also common for mobile devices to be used in conjunction with one or more desktop computers. For example, the user of a mobile device may also have access to, and use, a desktop computer at work, at home, or both. A user may typically run the same types of PIMs on both the desktop computer and the mobile device (although the particular versions of the PIMs may be somewhat different from the desktop computer to the mobile device). Thus, it is quite advantageous for the mobile device to be designed to be coupleable to the desktop computer to exchange information with, and share information with, the mobile device.
The user may also typically make changes to the PIMs both on the mobile device, and at the desktop. Therefore, it is advantageous for the PIMs on both the mobile device and the desktop to contain the most up-to-date information, regardless of whether recent changes to the PIMs have been made on the mobile device or the desktop computer. The process of coupling the mobile device with the desktop computer, and integrating the information stored by the PIMs on the mobile device and the desktop computer such that the two contain the same updated information is referred to as synchronization.
The information stored by the PIMs or other application programs contains objects, with objects being defined as a collection of properties. One of the properties of an object is a long term identification number (ID) for the object. While there is no defined upper or lower limit for the length of the long term ID object property, an example of a long term ID length is 56 bytes. Considerably longer and shorter long term ID lengths are common.
In some conventional synchronizing techniques, to search for changes or deletions of objects during synchronization, the long term IDs of the objects are used as a search parameter. Then, if a match of long-term IDs is found between an object in an object store and an object in a previous synchronization state table, a time stamp comparison was used to determine if the objects had been changed since the previous synchronization. As a secondary check, a cyclic redundancy check (CRC) property value of the objects, which is determined as a function of other properties of the object, has been used to verify that the objects had been changed in a manner which requires synchronization. Generally, since the size of the long term ID varies greatly from object to object, this method of searching for changes or deletions during synchronization can be very slow.
Disclosed are methods of searching a list or table of objects during synchronization between first and second object stores. One of the first and second object stores can be a previous synchronization state table. Using the method, a list of objects to be searched for changes and deletions is obtained during synchronization. The list of objects is then searched using as a search parameter an object signature determined as a function of particular properties associated with a particular object. In some embodiments of the present invention, the object signature is a 32-bit cyclic redundancy check (CRC) value calculated using other properties of the particular object. However, in other embodiments, longer and shorter object signatures are used. In yet other embodiments, the object signature is a substantially unique identifier of the properties associated with an object, but is not a CRC determined value. In some of these embodiments, the object signature is preferably less than about 128 bits in length.
Also disclosed are a computer system which implements the methods of the present invention, and a computer readable medium having computer executable instructions for performing the steps of the methods.